Glue gun



FIG. 1 is a right side elevational view of a glue gun showing my new design, the left side is identical;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a glue gun, as shown and described. 